Qualification of GaAs and AlGaAs by Optical and Surface Analysis Techniques

Optical techniques, including photoluminescence and infrared spectroscopies, have been investigated as a means of evaluating GaAs and AlGaAs wafers. Methods of surface analysis such as Auger Electron Spectroscopy and X-Ray Photoelectron Spectroscopy were used to support the optical measurements, as well as provide additional information, in the following areas: (1) evaluation of semi-insulating GaAs (a) by room temperature photoluminescence that showed strong intensity variations on a microscopic scale, suggestive of corresponding variations in semi-insulating properties, and (b) by low temperature photoluminescence that revealed substantial differences in carbon content in wafers with essentially the same resistivity; (2) self-quenching of the band-gap photoluminescence in GaAs at room temperature that appears to be connected with the formation and thickening of native oxide layers; (3) monitoring the course of post-implant annealing of Be-implanted GaAs and AlGaAs by measurements of photoluminescence at room temperature; (4) qualification of photoluminescence as an accurate means for determining composition in AlGaAs layers with aluminum content up to 0.58 mole fraction.